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with Paui I. Palmer, Tzung-May Fu, Dylan B. Millet, Dorian S. Abbot

MAPPING OF VOLATILE ORGANIC COMPOUND (VOC) EMISSIONS USING SATELLITE OBSERVATIONS OF FORMALDEHYDE COLUMNS Daniel J. Jacob. with Paui I. Palmer, Tzung-May Fu, Dylan B. Millet, Dorian S. Abbot. and Kelly V. Chance, Thomas Kurosu (Harvard SAO/CFA).

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with Paui I. Palmer, Tzung-May Fu, Dylan B. Millet, Dorian S. Abbot

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  1. MAPPING OF VOLATILE ORGANIC COMPOUND (VOC) EMISSIONS USING SATELLITE OBSERVATIONSOF FORMALDEHYDE COLUMNSDaniel J. Jacob with Paui I. Palmer, Tzung-May Fu, Dylan B. Millet, Dorian S. Abbot and Kelly V. Chance, Thomas Kurosu (Harvard SAO/CFA) supported by NASA Atmospheric Chemistry Modeling and Analysis Program

  2. SATELLITE OBSERVATIONS OF TROPOSPHERIC COMPOSITION…a rapidly growing resource!

  3. IMPORTANCE OF NON-METHANE VOC EMISSIONS FOR ATMOSPHERIC CHEMISTRY • Precursors of tropospheric ozone • Precursors of organic aerosols • Sinks of OH Alkanes, alkenes, aromatics… Isoprene, terpenes, oxygenates… Alkenes, aromatics, oxygenates… ~ 200 Tg C yr-1 ~ 600 Tg C yr-1 ~ 50 Tg C yr-1 Industry Vegetation Biomass burning

  4. SPACE-BASED MEASUREMENTS OF HCHO COLUMNSAS CONSTRAINTS ON VOC EMISSIONS solar backscatter 340 nm hn (l < 345 nm), OH Oxidation (OH, O3, NO3) VOC HCHO lifetime of hours many steps Emissions

  5. SPACE-BASED MEASUREMENTS OF ATMOSPHERIC COLUMNS BY SOLAR BACKSCATTER Examples: TOMS, GOME, SCIAMACHY, MODIS, MISR, OMI, OCO Applications to retrievals of O3, NO2, HCHO, BrO, CO, CO2, aerosols… absorption Backscattered intensity IB l1 l2 wavelength Slant optical depth Scattering by Earth surface and by atmosphere “Slant column” Vertical column The air mass factor (AMF) depends on viewing geometry and radiative transfer

  6. THE GOME INSTRUMENT • Instrument in polar sun-synchronous orbit, 10:30 a.m. observation time • 320x40 km2 field of view, three cross-track scenes • Complete global coverage in 3 days • Operational since 1995 • HCHO column is determined from backscattered solar radiance in 340 nm absorption band • Concurrent retrievals of cloud fractions, tops, optical depths

  7. FITTING OF HCHO SLANT COLUMNS FROM GOME SPECTRA ts = 1.0 ± 0.3 x1016 cm-2 Fitting uncertainty of 4x1015 molecules cm-3 corresponds to ~ 1 ppbv HCHO in lowest 2 km ts = 3.0 ± 0.4 x1016 cm-2 ts = 8.4 ± 0.7 x1016 cm-2 Chance et al. [2000]

  8. HCHO SLANT COLUMNS MEASURED BY GOME (JULY 1996) 2.5x1016 molecules cm-2 2 1.5 1 detection limit 0.5 South Atlantic Anomaly (disregard) 0 -0.5 High HCHO regions reflect VOC emissions from fires, biosphere, human activity

  9. q AIR MASS FACTOR (AMF) CONVERTS SLANT COLUMN WS TO VERTICAL COLUMN W “Geometric AMF” (AMFG) for non-scattering atmosphere: EARTH SURFACE

  10. IN SCATTERING ATMOSPHERE, AMF DEPENDS ON VERTICAL DISTRIBUTION OF ABSORBER 340 nm HCHO EARTH SURFACE Use GEOS-Chem chemical transport model to specify shape of vertical profile for given scene

  11. AMF FOR A SCATTERING ATMOSPHERE what GOME sees GOME sensitivity w(z) HCHO mixing ratio profile S(z) (GEOS-Chem) AMFG = 2.08 actual AMF = 0.71 Palmer et al. [2001]

  12. QUANTIFYING AMF ERRORS USING AIRCRAFT PROFILES ICARTT mission over North America (summer 2004) 0-10 km spirals and profiles during ICARTT: In situ HCHO, clouds, aerosol extinction Mean HCHO profiles in ICARTT Observed (Fried) Observed (Heikes) GEOS-Chem model (n = 89) Dylan B. Millet, Harvard Clouds are the principal source of error

  13. …compare to GEOS-Chem including GEIA biogenic VOC emissions and U.S. EPA anthropogenic VOC emissions GEOS-Chem vs. GOME: R = 0.83, bias = +14% FORMALDEHYDE COLUMNS FROM GOME: July 1996 means Palmer et al. [2003]

  14. SEASONALITY OF GOME HCHO COLUMNS (9/96-8/97)largely reflects seasonality of isoprene emissions GOME GEOS-Chem (GEIA) GOME GEOS-Chem (GEIA) MAR JUL APR AUG SEP MAY JUN OCT Abbot et al. [2003]

  15. INTERANNUAL VARIABILITY OF GOME HCHO COLUMNS Augusts 1995-2001: correlation with temperature anomaly explains some but not all of the HCHO column variability GOME HCHO Temp. anomaly GOME HCHO Temp. anomaly 1995 1999 1996 2000 2001 1997 Abbot et al. [2003] 1998

  16. RELATING HCHO COLUMNS TO VOC EMISSION hn (<345 nm), OH oxn. VOCi HCHO yield yi k ~ 0.5 h-1 Emission Ei smearing, displacement In absence of horizontal wind, mass balance for HCHO column WHCHO: Local linear relationship between HCHO and E … but wind smears this local relationship between WHCHO and Ei depending on the lifetime of the parent VOC with respect to HCHO production: Isoprene WHCHO a-pinene propane Distance downwind 100 km VOC source

  17. Box model simulations with state-of-science MCM v3.1 mechanism TIME-DEPENDENT HCHO YIELDS FROM VOC OXIDATION methylbutenol High HCHO signal from isoprene with little smearing, weak and smeared signal from terpenes; GEOS-Chem yields may be too low by 10-40% depending on NOx Palmer et al, [2005]

  18. HCHO COLUMN vs. ISOPRENE EMISSION RELATIONSHIPIN GEOS-Chem MODEL Results for U.S. quadrants in July 1996 simulation w/ 2ox2.5o horizontal resolution show: (1) dominance of isoprene emission as predictor of WHCHO variability; (2) linear relationship between the two Standard simulation NW NE R2 = 0.43 HCHO from simulation w/o Isoprene emission R2 = 0.51 Model HCHO column [1016 molec cm-2] R2 = 0.65 SW SE R2 = 0.49 We use this relationship to derive “top-down” isoprene emissions from the GOME HCHO column observations Isoprene emission [1013 atomC cm-2 s-1]

  19. GOME vs. MEGAN ISOPRENE EMISSION INVENTORIES (2001) MEGAN is a new inventory of isoprene emissions developed by Alex Guenther [Guenther et al., 2005] • Good accord for seasonal variation, regional distribution of emissions; • GOME 10-34% higher than MEGAN depending on month, differences in hot spot locations Palmer et al. [2005]

  20. EVALUATING GOME ISOPRENE EMISSION ESTIMATES vs. IN SITU FLUX MEASUREMENTS (2001) PROPHET forest site in northern Michigan (M. Pressley, WSU): also shown are local MEGAN isoperene emission inventory values Palmer et al. [2005]

  21. Amplitude and phase are highly reproducible YEAR-TO-YEAR VARIABILITY OF GOME HCHO OVER SOUTHEAST U.S. GOME HCHO Column [1016 molec cm-2] Southeast US average 32-38N; 100-85W P. I. Palmer (Harvard)

  22. WHAT DRIVES GOME HCHO TEMPORAL VARIABILITY OVER SOUTHEAST U.S. DURING MAY-SEPTEMBER? Monthly mean GOME HCHO vs. surface air temperature; MEGAN parameterization shown as fitted curve Temperature drives ~80% of the variance of monthly mean HCHO columns P.I. Palmer (Harvard)

  23. GOME HCHO COLUMNS OVER EAST ASIA (1996-2001) JAN APR JUL OCT AUG FEB MAY NOV JUN SEP MAR DEC Relationship to VOC emissions far more complex than for N. America; biomass burning, isoprene, anthropogenic VOCs, direct HCHO emission all contribute Tzung-May Fu (Harvard)

  24. APR JUL MAY AUG JUN SEP GOME vs. GEOS-Chem HCHO COLUMNS OVER EAST ASIA MEGAN biogenic emission inventory is far too low T. M. Fu (Harvard)

  25. VOC CONTRIBUTIONS TO HCHO PRODUCTION IN CHINESE CITIES (JAN-FEB 2001) Vehicle-generated xylenes could make a large contribution to HCHO columns NC CC Ethane 0.3 % Benzene 0.4 % Propane 0.3 % Toluene 2.4 % ALK4 5.1 % Xylene 20.2 % Ethene 19 % Isoprene 8.2 % PRPE 43 % WC SC B. Barletta (UCI), T.-M. Fu (Harvard)

  26. PRELIMINARY HCHO COLUMN DATA FROM OMI(launched on Aura in July 2004) 26 Day Average: 24 September – 19 October 2004 K. Chance and T. Kurosu (Harvard CFA)

  27. OMI HCHO RETRIEVALS AND MODIS FIRE COUNTS Chongqing(Red Basin) Jakarta

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